PTL 1 discloses a battery block in which in a metal casing having battery cell housing parts capable of housing a large number of battery cells, lithium ion battery cells of which a number is smaller than a number of the battery cell housing parts, are housed, and dummy cells having no electric energy are housed in housing parts housing no battery cell.
PTL 2 describes a pack battery configured to include a combination of a plurality of cell cases capable of housing a predetermined number of battery cells, and in the pack battery, a number of the battery cells housed in one of the cell cases is set to a number smaller than the predetermined number, and consequently an optimum output voltage or current capacity is realized according to uses.